client/server apps

Hello koders, i am a beginner and i am building a two apps system one i buy from and generates the QR code of the personal paypal account, the other app is a code scanner with a business PayPal account, it scan the code from the customer app then it do the transaction.
I need help with the PayPal part if anyone of you guys have an idea

What have you tried yourself. You probably get more help if you show what you tried.

This extension may help you